Protective guard for a mortise type lock

ABSTRACT

A protective guard is disclosed for a mortise lock having a spindle hole comprising a disc of hardened metal. Located centrally with respect to one side of the disc is a stub extending perpendicularly therefrom. The stub terminates in a radially extending flange. A bushing is positioned over the stub between the disc and the flange whereby the flange retains the bushing. The stub with its bushing is adapted to be friction fitted into the spindle hole of the lock. The disc and stub may be rotated but the bushing remains stationary. The protective guard prevents access to the spindle hole.

Y 0 United States Patent 1 1 1 3,741,597 Ohno June 26, 1973 [54] PROTECTIVE GUARD FOR A MORTISE 1,529,775 3/1925 Dcnnet t 292/307 R X TYPE LOCK 7 2,119,994 6/1938 Love 292/307 R X 2,594,407 4/1952 Earnest 70/259 X [75] Inventor: Richard J. Ohno, Branford, Conn. [73] Assignee: Sargent and Company, New Haven, Examiner-Robert Wolfe C Attorney-Eric P. Schellin et al. [22] Filed: :"Nov. 16 1971 [57] ABSTRACT [21] Appl' 199371 A protective guard is disclosed for a mortise lock having a spindle hole comprising a disc of hardened metal. 521 US. Cl 292/1, 70/417, 292/346 Leeeted eemrelly wiih reerieet to one Side of the disc 51 1111. C1 E05b 15/16 is a stub extending perpendicularly therefrem- The stub 58 Field of Search 292/1, 346, 307 R; terminates/in a radially extending flange A bushing is 70 431, 417, 41g 423 424 42 42g 4 0 positioned over the stub between the disc and the 259; 42 R flange whereby the flange retains the bushing. The stub with its bushing is adapted to be friction fitted into the [5 v Reference-sci! spindle hole of the lock. The disc and stub may be ro- E ATES- PATENTS tated but the bushing remains stationary. The protecl,5 59,699 11/1925 Herold 16/42 R twe guard prevents access to the spmdle hole. 2,548,104 4/1951 Frison 292/307 R X 3 Claims, 6 Drawing Figures PATENTED M26 I975 IN VENTOR RICHARD J. OHNO ATTORNEYS PROTECTIVE GUARD FOR A MORTISE TYPE LOCK BACKGROUND OF THE INVENTION Mortise locks have been used for many years. Due to the neat appearance they present they are favored over locks which are merely secured to one surface of a door. Furthermore, they are favored over the many locks now on the market having operating mechanisms directly associated with the door knobs. One great advantage of the mortise lock is in its ability to combine a mechanical lock with a dead bolt function to ensure greater security. Usually, a mortise lock is constructed with spindle holes which are readily accessible from both sides of its housing. This is to facilitate its use either on the right side or left side of a door. Of course, in usual practice only the spindle hole for the dead bolt on one side is used for a manual operator. This side is on the inside, that is, opposite to the key cylinder side.

In this manner the dead bolt may be operated manually by means of a thumb and finger knob. The other side of the spindle hole is not accessible as it is covered by the outer portion of the door. 7

In a wood door, after mortising, the door has only a thin section of wood remaining (oftentimes as little as 3/16 inch) between the lock body and exterior face of the door. A metal door, being hollow to begin with has only the stock thickness of metal. Even though the spindle hole is not visible from the exterior; the exact location of the center of the dead bolt spindle hole can be easily determined since its position is always constant, relative to the locks conventional cylinder or the knob. It is possible to obtain access to the spindle hole by use of a drill, awl, sharpened screw driver or other tool by penetrating the wood or metal at the correct spot which, as was said, can be determined. When the spindle hole is breached in this manner, the hub can then be turned and the dead bolt can be retracted to unlock the door.

BRIEF DESCRIPTION OF THE INVENTION To guard against a breach of security, the present invention relates to a device which is employed to block off the dead bolt spindle hole. The device of the present invention is a disc of hardened metal with a stub thereon. The stub carrying the disc is inserted in the spindle hole and the disc lies on the surface of the mortise lock. When the lock is in place in the door the disc is sandwiched between the wood or metal of the door and the lock. The disc is mounted so that it is freely rotatable in the spindle hub. The rotation of the disc does not affect the spindle hub so the dead bolt cannot be retracted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a side perspective view of a mortise lock with the protective guard exploded therefrom.

FIG. 2 is a similar view with the protective guard in position.

FIG. 3 is a perspective view of one side of the guard.

FIG. 4 is a side plan view of the guard.

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 4.

FIG. 6 is a similar view as FIG. 3 with the bushing exploded therefrom.

DETAILED DESCRIPTION OF THE INVENTION the exterior of the door which is not to have the conventional thumb and finger knob, for operation of the dead bolt, it is this side that is to receive the protective guard. The spindle hole having the hub to operate the dead bolt is depiected by reference numeral 15. The cylinder receiving hole 16 is seen to be located directly thereabove.

The protective guard 21 has a stub 22 which is inserted in the spindle hole 15. The result is to present a face as shown in FIG. 2 where the disc covers not only the spindle hole 15 but a considerable portion thereabout.

From a more detailed description of the invention, particularly, FIGS. 3-6, one can see with greater clarity the protective guard 21. Relative thereto it will be seen that the protective guard 21 includes a metal disc 23 which should be of hardened metal. The disc 23 depicted is circular in nature, but any flat polygonal structure would do as well. Substantially,centrally, is a stub 22 which is perpendicular to the disc. It may be welded or rivetted to the disc or affixed thereto by any other suitable manner. From FIG. 6 one can see that the stub terminates in a head which is a radially extending flange 24. A bushing 25 having a diameter larger than the stub is positioned over the stub between the surface of the disc 23 and the flange 24. The bushing is seen to be split longitudinally so that it may be expanded prior to being passed over the flange 24 and thereby locked into position. FIGS. 3, 4 and 5 clearly portray the bushing 25 in position. The bushing 25 is freely rotatable about the stub. The purpose of this will be soon demonstrated in the following.

With the protective guard assembled in the fashion shown in FIGS. 3, 4 and 5, there is presented the protective guard 21 as shown in FIG. 1. The stub 22 having thereon the bushing 25 is inserted into the spindle hole. The bushing is designed to achieve a friction fit with the inner periphery of the spindle hole. The diameter of the stub is adjusted so that together with the bushing it will indeed achieve a good friction fit. On the other hand as the bushing is freely rotatable about the stub, it will be seen that the disc may be easily rotated with the stub as its axis. However the bushing being free of the stub will not rotate so that rotation of the disc and its stub will not affect the hub of the spindle hole at all.

In use the outer surface of the protective guard will be exposed when a hole is drilled or punched into the door by an illegal entrant. As the disc is considerably larger than any hole usually made with conventional hand tools, access to the spindle hole is prevented as the disc cannot be removed. Only a much larger hole in the door will permit removal of the disc. An attempt to rotate the disc after a hole is breached through the door will not meet with any undue resistance. But as a result of the use of the bushing the disc will be permitted to rotate freely without turning the spindle hub to retract the bolt. As the disc is of hardened metal it cannot be punctured as readily as the remaining portion of a wooden door or of the usual grade steel of a metal door. With the protective guard in place a much larger hole must be made before the guard can be removed.

While the bushing shown above is of the split variety, a full annular type is also contemplated within the purview of the invention. In such an instance the bushing would have directional edges so that once pressed in place it would grab and lock behind the flange. The bushing may be a sleeve of metal or plastic.

The invention includes the concept of the protective guard separate from the mortise lock, so that the installer of the lock hardware first determines the applicable hand for the door and presses the protective guard into a predetermined dead bolt spindle hole on the side toward the outside face of the door. The disc 23 is sufficiently thin so that no special effort need be made to enlarge the mortise configuration and dimension much beyond that ordinarily employed.

What is claimed is:

1. In a lock of the mortise type having dead bolt means including a spindle hole on opposite surfaces whereby said dead bolt is operated by spindle means the improvement comprising a disc of hardened metal,

a relatively centrally positioned stub extending perpendicularly from one side of said disc, said stub terminating in a radially extending flange, a bushing positioned over said stub between said disc and said flange whereby said flange holds the bushing in place, said stub with said bushing is positioned in said spindle hole, the side of the disc carrying said stub with said bushing is in confrontation with one of the surfaces of said mortise lock, the stub with said bushing is adapted to provide a friction fit between the outer surface of said bushing and the spindle hole whereby the stub and disc may freely rotate while said bushing remains stationary.

2. The lock of claim 1 wherein the bushing is split longitudinally.

3. The lock of claim 1 wherein the thickness of the bushing is greater than the height of said radially extending flange. 

1. In a lock of the mortise type having dead bolt means including a spindle hole on opposite surfaces whereby said dead bolt is operated by spindle means the improvement comprising a disc of hardened metal, a relatively centrally positioned stub extending perpendicularly from one side of said disc, said stub terminating in a radially extending flange, a bushing positioned over said stub between said disc and said flange whereby said flange holds the bushing in place, said stub with said bushing is positioned in said spindle hole, the side of the disc carrying said stub with said bushing is in confrontation with one of the surfaces of said mortise lock, the stub with said bushing is adapted to provide a friction fit between the outer surface of said bushing and the spindle hole whereby the stub and disc may freely rotate while said bushing remains stationary.
 2. The lock of claim 1 wherein the bushing is split longitudinally.
 3. The lock of claim 1 wherein the thickness of the bushing is greater than the height of said radially extending flange. 